Decoiling of a coiled strip

ABSTRACT

An unwinding device ( 1 ) for unwinding a strip ( 5 ) which had been wound to form a coil ( 3 ), in order for the unwound strip ( 5 ) to be hot-rolled. The unwinding device ( 1 ) has at least two bottom rollers ( 7 ) for supporting the coil ( 3 ) on the lower side of the coil, a detaching mechanism ( 9 ) for detaching a strip end ( 11 ) from the coil ( 3 ) on an unwinding side of the coil, and a downholder roller ( 13 ), ( 14 ) which is disposed at the coil ( 3 ) such that the downholder roller ( 13 ), ( 14 ) stabilizes the position of the coil ( 3 ) when the strip end ( 11 ) is being detached.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§371 national phase conversionof PCT/EP2015/057288, filed Apr. 2, 2015, which claims priority ofEuropean Patent Application No. 14164068.0, filed Apr. 9, 2014, thecontents of which are incorporated by reference herein. The PCTInternational Application was published in the German language.

TECHNICAL FIELD

The invention relates to an unwinding device and to a method forunwinding a strip of metal which has been wound to form a coil, in orderfor the strip to be hot-rolled.

TECHNICAL BACKGROUND

In hot-rolling plants, pre-rolled strips are often wound to form aso-called coil. In order for the strips to be wound and/or unwound,winding and/or unwinding devices, which are also referred to as coilingboxes, are used. Hot-rolling plants having coiling boxes offeradvantages in terms of the temperature, rolling speed, and rolling forcewhich remain constant across the strip length. On the one hand,increasingly stronger material is being produced by hot-rolling, and themaximum strip thickness, in particular for tube grades, is beingincreased, on the other hand. One method for increasing the strength andtenacity of the material lies in thermo-mechanical rolling, for example,in which rolling is performed at very low temperatures in a finishingmill. Due to the increase in terms of strength and thickness, and/or interms of the reduction in the temperature of the strips, there is anincreasing demand for winding and/or unwinding thicker, colder, andstronger pre-strips in a coiling box.

DE 10339191 A1 discloses a method and a device for expanding theapplication of a winding and unwinding station (coiling box) between theroughing mill and the finishing mill for rolled strip material inhot-rolling works. It is inter alia proposed herein for the treatment oflower coil weights that a contact pressure which is directed toward theroller conveyor is forced upon the coil to be unwound in a mandrel-freecoiling box.

JP H07 148522 A discloses a winding device for unwinding a coil, havinga contact-pressure device for providing contact pressure to the coil.

SUMMARY OF THE INVENTION

The invention is based on the object of stating an improved unwindingdevice for unwinding a strip which has been wound to form a coil, inorder for the strip to be hot-rolled. Furthermore, the invention isbased on the object of stating an improved method for unwinding a stripwhich has been wound to form a coil, in order for the strip to behot-rolled.

An unwinding device according to the invention for unwinding a stripwhich has been wound to form a coil, in order for that strip to behot-rolled, comprises at least two bottom rollers for supporting thecoil on the lower side, a strip-end detaching mechanism for detaching astrip end from the coil on an unwinding side, and a downholder rollerwhich is disposed on the coil in such a manner that the downholderroller stabilizes the position of the coil when the strip end is beingdetached.

The downholder roller herein is disposed at a fixed spacing from anexternal surface of the coil.

An unwinding device of this type advantageously makes it possible toprevent or to restrict a positional displacement of the coil that mayarise when the strip end is being detached from the coil. Positionaldisplacements of the coil of this type in particular exist in a coil ofrelatively strong, thick, and/or cool strips being lifted from thebottom rollers when the strip end is being detached from the coil whenthe force-engagement point lies outside a region which is supported bythe bottom rollers. The invention prevents or reduces positionaldisplacements of this type in a simple and cost-effective manner by wayof a downholder roller which is disposed on the coil, thus enablingrisk-free unwinding of strips from a high-strength material, of coolstrips, and of thick strips. By disposing the downholder roller at afixed spacing from an external surface of the coil, a positionalvariation of the coil which displaces the coil beyond the spacing fromthe downholder roller is advantageously avoided.

One design embodiment of the invention provides that the downholderroller is disposed on an upper side of the coil.

An alternative design embodiment of the invention provides that thedownholder roller is disposed on the unwinding side on the coil.

In the case of the two aforementioned design embodiments of theinvention, the downholder roller is disposed above or on the unwindingside of the coil such that the downholder roller may advantageouslyprevent positional displacements of the coil that may arise when thestrip end is being detached from the coil.

One further design embodiment of the invention provides that thelongitudinal axes of the downholder roller and of the bottom rollers aredisposed so as to be mutually parallel.

On account thereof, the downholder roller and the bottom rollers in anadvantageous manner are of identical mutual alignment such that thelongitudinal axes thereof run in the same direction as a winding axis ofthe coil.

In the method according to the invention for unwinding a strip which hasbeen wound to form a coil, the coil on the lower side is supported bymeans of at least two bottom rollers, a strip end on an unwinding sideis detached from the coil by means of a strip-end detaching mechanism,and a downholder roller is disposed at the coil in such a manner thatthe position of the coil is stabilized when the strip end is beingdetached. The downholder roller herein is disposed at a fixed spacingfrom an external surface of the coil.

Due to the advantages which have already been mentioned above, themethod prevents or reduces positional displacements of the coil that mayarise when the strip end is being detached from the coil.

Design embodiments of the method correspond to the design embodiments ofthe unwinding device according to the invention, offering the advantageswhich have already been mentioned above. These design embodimentsprovide that the downholder roller is disposed on an upper side of thecoil, or on the unwinding side on the coil, and/or that the longitudinalaxes of the downholder roller and of the bottom rollers are disposed soas to be mutually parallel, and/or that the downholder roller isdisposed at a fixed spacing from an external surface of the coil.

The above-described properties, features, and advantages of thisinvention, and the manner by way of which the former are achieved, willbe more clearly and better understood in conjunction with the followingdescription of an exemplary embodiment which will be explained in moredetail in conjunction with a drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The single FIGURE schematically shows a side view of an unwinding devicefor unwinding a strip which has been wound to form a coil, in order forthe strip to be hot-rolled.

DESCRIPTION OF AN EMBODIMENT

The unwinding device 1 comprises two bottom rollers 7 for supporting thecoil 3 on the lower side, a strip-end detaching mechanism 9 fordetaching a strip end 11 from the coil 3 on an unwinding side, and adownholder roller 13 which is disposed on the coil 3 in such a mannerthat the downholder roller 13 stabilizes the position of the coil 3 whenthe strip end 11 is being detached.

In the exemplary embodiment which is illustrated in the FIGURE, adownholder roller 13 may be disposed at an upper side of the coil, so asto be at a fixed spacing from an external surface of the coil.Alternatively, a downholder roller 14 may be disposed at the unwindingside 15 of the coil 3, as shown in broken line. The downholder roller 13or 14 is normally out of contact with the coil and contacts the coilwhen the strip end is detached, so that the downholder roller serves asa mechanical stop for the coil.

The longitudinal axes of the downholder roller 13, 14 and of the bottomrollers 7 are disposed so as to be mutually parallel. The strip-enddetaching mechanism 9 is configured as a pivotable arm. Mountings of thedownholder roller 13, 14 in the gap between the coil and the strip-enddetaching mechanism 9 are not illustrated. The downholder roller is heldat a fixed spacing from the external surface of the coil.

Furthermore, there are transfer rollers 15 and two drive rollers 17 forconveying the unwound strip 5. The drive rollers 17 are disposed on topof one another. The strip 5 is guided by way of the transfer rollers 15to the drive rollers 17 and is pulled through between the drive rollers17.

While the invention has been illustrated and described in more detail byway of preferred exemplary embodiments, the invention is not limited bythe disclosed examples, and other variations may be derived therefrom bya person skilled in the art without departing from the scope of theinvention.

LIST OF REFERENCE SIGNS

1 Unwinding device

3 Coil

5 Strip

7 Bottom roller

9 Strip-end detaching mechanism

11 Strip end

13 Downholder roller

15 Transfer roller

17 Drive roller

1.-4. (canceled)
 5. A method for unwinding a strip which had been woundto form a coil, the method comprising: supporting the coil on the lowerside below the coil by at least two bottom rollers; detaching a stripend from the coil on an unwinding side of the coil by a strip-enddetaching mechanism; and disposing a downholder roller at a fixedspacing from an external surface of the coil in a manner to stabilizethe position of the coil when the strip end is being detached.
 6. Themethod as claimed in claim 5, further comprising disposing thedownholder roller at an upper side of the coil.
 7. The method as claimedin claim 5, further comprising disposing the downholder roller at theunwinding side on the coil.
 8. The method as claimed in claim 5, furthercomprising disposing respective longitudinal axes of the downholderroller and of the bottom rollers to be mutually parallel.